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Part Number 55000-843IMC
The Context Plus XP95 Switch Monitor with Isolator is designed to monitor the state of one or more single pole, volt-free contacts connected on a single pair of cables and to report the status to Context Plus compatible control equipment.
The Switch Monitor provides four input states to the control equipment: ‘Normal’,
‘Fault’, ‘Pre-alarm’ and ‘Alarm’. The Switch Monitor has a red LED to indicate an alarm and two yellow LEDs to indicate a switch input wiring fault or a loop shortcircuit wiring fault.
The Switch Monitor is fitted with a bi-directional short-circuit isolator and will be unaffected by a single short-circuit on either loop input or output.
The Switch Monitor is loop powered and operates at 17–28V DC with protocol voltage pulses of 5–9V. It is designed to accept a maximum line resistance of 50 Ω .
The end-of-line resistor required is 20k Ω .
The Switch Monitor is supplied with a back box for surface mounting and is intended for indoor use only.
Three LEDs, one red and two yellow, are visible through the front cover of the enclosure.
The red LED can be illuminated under CIE control in the event of an alarm being detected.
One yellow LED is illuminated in the event of a fault condition being detected in the monitoring circuit and cannot be controlled by the CIE.
The other LED is illuminated whenever the built-in isolator has sensed a shortcircuit loop fault.
Technical Data
Minimum loop operating voltage in normal
conditions: 17V DC
Maximum loop operating voltage: 28V DC
Maximum current consumption at 24V:
Switch-on surge, max 150ms: 3.5mA
Quiescent, 20k Ω EOL fitted: 1.25mA
LED off, switch input closed: 1.5mA
LED on, switch input closed: 3.5mA
LED on, switch input s/c: 3.6mA
Maximum continuous current: 1A
Maximum switching current: 3A
On resistance: 0.2
Ω
Switch input monitoring voltage: 9–11V DC
Maximum cable resistance: 50 Ω
Operating temperature: –20°C to +70°C
Humidity (no condensation): 0–95%RH
Shock, vibration and impact: to GEI 1-052
IP rating: 54
Radiated and conducted RF emissions to:
BS EN50081-1 & 2
Radiated and conducted RF immunity to:
BS EN50130-4
Dimensions of switch Monitor (surface mount):
150 x 90 x 48mm
Weight: 240g

Context
Plus
Part Number 55000-847IMC
The Context Plus XP95 Input/Output Unit with Isolator provides two voltage-free, single pole, change-over relay outputs, a single monitored switch input and an unmonitored, non-polarised opto-coupled input.
The Input/Output Unit supervises one or more normally-open switches connected to a single pair of cables. It is set to return an analogue value of 4 in the event of an open or short-circuit fault and 16 during normal operation. The status of the inputs is reported by means of two input bits.
The change-over contacts are operated by an output bit.
The Input/Output unit is fitted with a bi-directional short-circuit isolator and will be unaffected by loop short-circuits on either loop input or output.
The Input/Output Unit is loop powered and operates at 17-28V DC with protocol voltage pulses of 5-9V. No electrical supply greater than 50V AC rms or 75V DC should be connected to any terminal of this Input/Output Unit.
The Input/Output Unit is normally supplied with a backbox for surface mounting. It is also available without the backbox for flush mounting. Both versions are designed for indoor use only.
Four LEDs, two red and two yellow, are visible through the front cover of the enclosure.
One red LED is illuminated to indicate that the relay is set. The second red LED is illuminated to indicate that the switch input is closed.
One yellow LED is illuminated whenever a fault condition (open or short circuit) has been detected.
The other LED is illuminated whenever the built-in isolator has sensed a shortcircuit loop fault.
The enclosure is moulded from white self-extinguishing polycarbonate.
Technical Data
Minimum loop operating voltage in normal
conditions: 17V DC
Maximum loop operating voltage: 28V DC
Max. current consumption at 24V DC no protocol
Switch-on surge, max 150ms: 3.5mA
Quiescent, 20k Ω EOL fitted: 1.25mA
Switch input closed ‘switch closed’ LED on: 2.5mA
Switch input closed (LED disabled): 1.5mA
Any other condition (max 2 LEDs on): 3.5mA
Relay operated: 2mA
Switch input monitoring voltage (open-circuit
condition): 9–11V DC
Maximum cable resistance: 50 Ω
Opto-coupled input
Maximum voltage: 35V DC
Impedance: 10k Ω
Relay output contact rating at 30V AC or DC (inductive
or resistive): 1A
Relay output wetting current at 10mV DC: 10µA
On resistance 0.2
Ω
Maximum continuous current: 1A
Maximum switching current: 3A
Maximum load: 20 Context Plus detectors
Operating temperature: –20°C to +70°C
Humidity (no condensation) : 0–95% RH
Shock, vibration and impact: to GEI 1-052
IP rating: 54
Radiated and conducted RF emissions to:
BS EN 50081-–1 & 2
Radiated and conducted RF immunity to:
BS EN 50130–4
Dimensions of Input/Output Unit (surface mount):
150 x 90 x 48mm;
Weight: 240g
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Part Number 55000-845IMC
The Context Plus XP95 Zone Monitor with Isolator powers and controls the operation of a zone of up to 20 Series 65 conventional fire detectors from a loop of Context Plus analogue addressable detectors and interfaces.
The Zone Monitor with Isolator is factory preset to return an analogue value of 16 when all detectors on the zone are in quiescent state and 64 when a detector changes to the alarm state. The Zone Monitor with Isolator latches in the alarm state.
A 5.1k
Ω end-of-line resistor is fitted to detector cables for open- and short-circuit faults. Alternatively, an active end-of-line monitor may be used in conjunction with diode bases and a capacitor of up to 50µF fitted at the Zone Monitor with
Isolator wiring terminals.
In either case an analogue value of 4 is transmitted during open- or short-circuit faults. The Zone Monitor with Isolator is fitted with a bi-directional short circuit isolator and will be unaffected by loop short circuits on either the loop input or loop output.
The Zone Monitor with Isolator is loop powered and operates at 17–28V DC with protocol pulses of 5–9V.
The Zone Monitor with Isolator is normally supplied with a backbox for surface mounting, and is also available without the backbox for flush mounting. Both versions are for indoor use only.
Two LEDs, one red and one yellow, are visible through the front cover of the enclosure.
The red LED is illuminated to indicate that a fire alarm condition has been detected on the zone wiring.
The yellow LED is illuminated whenever the built-in isolator has sensed a short circuit loop fault.
The backbox is a polycarbonate moulding.
NOTES ON USE
1. Zone voltage is regulated to 19 ± 1V for any loop voltage greater than 22V. If the loop voltage falls below 22V, the zone voltage is approximately 1.5V below the loop voltage. It is important to ensure that under worst-case conditions, the zone voltage is above the minimum operating voltage for the conventional detectors.
2. Alarm conditions are latched internally by the Zone Monitor with Isolator. It is therefore necessary to reset the alarm even if non-latching conventional detectors are used.
3. Manual call points can be located at any point in the zone wiring if active end-of-line monitoring with diode detector bases is used. If a 5.1k
Ω resistor is used for monitoring, manual call points must be connected between the Zone Monitor with Isolator and the first detector.
Technical Data
Context Plus line voltage: 17V-28V DC
Zone voltage (loop voltage ≥ 22V): 19V±1V
Zone voltage (loop voltage <22V): Loop voltage -1.5V
Maximum current consumption at 24V (5.1K
Ω EOL):
Switch-on surge, max 150ms: 3.5mA
Quiescent: 4mA + detector load
Alarm: 11mA (19mA when increased current enabled)
Short circuit: 11mA
End of line resistor value: 5.1K
Ω ± 5% 1/3W
Stabilisation time on power up: 4 seconds
Maximum capacitor on zone terminals: 5µF
Operating temperature: –20°C to +70°C
Humidity (no condensation): 0–95%RH
Shock, vibration and impact: to GEI 1-052
IP rating: 54
Radiated and conducted RF emissions to:
BS EN50081-1 & 2
Radiated and conducted RF immunity to:
BS EN50130-4
Dimensions of Zone Monitor (surface mount):
150 x 90 x 48mm
Weight: 230g

Context
Plus
Part Number 55000-852IMC
MECHANICAL CONSTRUCTION
The Sounder Control Unit with
Isolator is normally supplied with a backbox for surface mounting. It is also available without the backbox for flush mounting. The mouldings are made from polycarbonate material. Both versions are for indoor use only.
Three LEDs, one red, two yellow, are visible through the front cover of the enclosure. The red one pulses or is illuminated continuously to indicate that the sounders are, respectively, pulsed or switched on continuously.
One yellow LED is illuminated whenever a fault has been detected.
The other LED is illuminated whenever the built-in isolator has sensed a short-circuit loop fault.
FAULT MONITORING
In addition to the monitoring of open and short circuit faults on the sounder wiring, the Unit has a facility to monitor the presence and polarity of the external PSU. This is achieved by a fault monitoring circuit which also includes an input to monitor a volt-free contact (such as a fault relay in the external PSU). A three-way terminal block is provided for connection of normally-open or normally-closed fault contacts to this fault input. Note that a wire link must be fitted between the ‘COM’ and ‘N/C’ terminals if the fault input is not used or if a normally-open contact is monitored.
The Context Plus XP95 Sounder Control Unit with Isolator is used to control the operation of a zone of externally powered sounders and to report their status to
Context Plus-compatible control equipment.
FEATURES
The Sounder Control Unit with Isolator allows sounders to be operated continuously or pulsed, 1 second on, 1 second off. Sounders may be operated individually or in groups and, whichever address mode has been applied, may be synchronised when in pulsed operation.
An opto-coupled input is provided to monitor the state of the external power supply.
In normal operation the Sounder Control Unit with Isolator returns a pre-set analogue value of 16, but in the event of an open or short-circuit fault or of a fault in the external power supply, the unit returns a pre-set analogue value of 4.
The Sounder Control Unit with Isolator is fitted with a bi-directional short-circuit isolator and will be unaffected by loop short-circuits on either loop input or output.
ELECTRICAL CONSIDERATIONS
The Sounder Control Unit with Isolator is line powered and operates at 17–28V
DC. It requires a local power supply of 9–32V DC to power the external load, which may be up to 1.25A. A polarising diode is required with each alarm device, as sounders are operated by voltage reversal, provided by a double-pole changeover relay. The sounder circuit is protected by a miniature (TR5) fuse rated at 1A.
ADDRESSING
The Sounder Control Unit with Isolator responds to its own individual address set with a 7-segment DIL switch. It also responds both to a group address, set by means of a 4-segment DIL switch, and to a pulsed-mode synchronisation address which is embedded in the unit.
Addresses 1 to 111 are used exclusively for individual addresses (if “0” is selected on the DIL switch, the Sounder Control Unit with Isolator will return a pre-set analogue value of 4 to signal a fault); addresses 112 to 126 are used for group addressing, while the synchronisation address, to which all units respond, is “0”.
Any Sounder Control Unit on a loop may be freely assigned to a group. The address for any group must be chosen from the range 112–126.
Addresses 112 to 126 may be used as individual addresses but only if the
4-segment DIL switch is set to 127 – group addressing is then disabled. If the
4-segment DIL switch were set to any number other than 127, a pre-set analogue value of 4 would be transmitted to indicate a fault.
Technical Data
Minimum loop operating voltage in normal
conditions : 17V DC
Maximum loop operating voltage: 28V DC
Sounder Control Data
Current consumption, loop, at 24V:
Switch-on surge, max 100ms: 2.6mA
Quiescent, 10k Ω EOL fitted : 1.95mA
Sounders operated: 1.7mA
Fault (yellow LED on): 3.6mA
Sounder line short circuit: 2.8mA
Current consumption, external supply:
Relay off: 1mA at 9V; 3mA at 32V
Sounders and red LED on: 44mA at 9V (+ sounder load); 47mA at 32V (+ sounder load)
Sounder output monitoring voltage (open-circuit
condition): 9–11V DC
Maximum sounder circuit voltage: 32V DC
Maximum sounder circuit current (inductive or resistive): 1A at 30V DC
On resistance: 0.2
Ω
Maximum continuous current: 1A
Maximum switching current: 3A
Maximum load: 20 Context Plus detectors
Operating temperature: –20°C to +70°C
Humidity (no condensation) : 0–95%RH
Shock, vibration and impact: to GEI 1– 052
IP rating: 54
Radiated and conducted RF emissions to:
BS EN 50081-–1 & 2
Radiated and conducted RF immunity to:
BS EN 50130–4
Dimensions of Sounder Control Unit with Isolator
(surface mount): 150 x 90 x 48mm
Weight: 240g
Page 25

Analogue addressable fire detection systems are usually designed as loops, with the connecting wires starting and finishing at the control panel. Detectors and interfaces are connected at intervals along the cables. Depending on the local regulations, manual call points and sounders are connected either to the same loop or to other, dedicated loops. Spurs may be connected at any point of the loop, either directly from the loop wires or from an interface such as a Zone Monitor.
Short circuits do not occur very often but, when they do, the consequences can be serious, possibly making the affected loop entirely inoperative. It is for this reason that isolating circuits have been designed and incorporated into various devices that are connected to the loop. The purpose of these isolating circuits is to protect the loop in the event of a short circuit by disconnecting the part of the loop where the short circuit has occurred. When the short circuit fault has been rectified, the isolating circuitry reconnects the affected section of the loop.
Normally an isolator should be included on every wiring transition between zones, thus ensuring that a single short circuit fault only affects one zone only or part thereof.
Isolating circuits are delivered as stand-alone isolators with their own mounting bases or as printed circuit boards in a version of the detector mounting bases known as ‘isolating bases’. Isolating circuits are also fitted to interfaces such as
Input/Output Units or Sounder Control Units. Isolating circuits are intended for use with Context Plus detectors and interfaces. Isolating circuits are polarity sensitive and normally switch the negative line of the loop.
Context Plus isolating circuits allow the connection of between one and twenty detectors or the equivalent load between isolators. Detectors fitted to isolating bases and interfaces with built-in isolating circuits remain operative when an adjacent loop section is in the isolated state. The isolated state is normally indicated by an illuminated yellow
LED on the isolating unit.
Under normal operating conditions the isolating circuit provides a low resistance of 0.2
Ω or lower in either direction.
If the loop voltage falls to 14±0.4V the isolator will switch from the closed state to the open state in order to isolate the loop ‘in’ and ‘out’ lines.
The isolated section is tested every four seconds with a current pulse and is automatically re-connected when the load resistance is 175 Ω or greater. The current pulses are drawn from the loop and it is important for correct operation of the system that the pulse load be included in the loop calculation made for any system.
Up to 20 detectors or the equivalent load may be connected between two isolating circuits. Interfaces and sounders are counted as one detector for every milliampere of switch-on surge current. Interfaces with integral isolation can be powered from either side of the isolator. The switch-on surge current is counted as one detector for every milliampere of switch-on surge current and must be included with the calculation for each of the adjacent sections of the loop.
It is essential that compatibility of panel and isolating device be fully established when designing a fire detection system.
Context Plus offers a software program with which the viability of a design can be checked.
For a copy of the program, entitled LoopCalc, contact our sales desk.
Technical Data
Minimum loop operating voltage in normal conditions: 17V DC
Maximum loop operating voltage: 28V DC
Minimum protocol pulse: 5V
Power-up time: <10ms
Quiescent current: 18V = 23µA; 24V = 35µA; 28V = 43µA
Current in isolated state: 18V = 4.0mA; 24V = 5.4mA; 28V = 6.4mA
Maximum loop current: 1A continuous; 3A short-circuit switching
Maximum load : 20 Context Plus XP95 detectors or equivalent
Maximum ‘on’ resistance: 0.2
Ω
Isolation indication: Yellow LED
Isolation voltage (isolator opens): 14±0.4V
Reconnection voltage: 15.8±0.4V
Reconnection resistance: 175 Ω
Isolation time: 50µs
Operating humidity: 0–95%RH non-condensing
Operating temperature: –20 to +60°C
Storage temperature: –30 to +80°C
Design environment: indoor use only
Note: all detectors and other devices between any two isolators or isolating devices should be in the same fire zone, because communications with them will be lost if a short-circuit occurs between isolators.
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